Emdash source with visual editor image upload fix

Fixes:
1. media.ts: wrap placeholder generation in try-catch
2. toolbar.ts: check r.ok, display error message in popover

packages/core/tests/unit/query-collection-bucketing.test.ts

@@ -0,0 +1,91 @@
+import type { Kysely } from "kysely";
+import { describe, it, expect, beforeEach, afterEach } from "vitest";
+
+import { handleContentCreate } from "../../src/api/index.js";
+import type { Database } from "../../src/database/types.js";
+import { emdashLoader } from "../../src/loader.js";
+import { bucketFilter, sliceCollectionResult } from "../../src/query.js";
+import { runWithContext } from "../../src/request-context.js";
+import { setupTestDatabaseWithCollections, teardownTestDatabase } from "../utils/test-db.js";
+
+describe("getEmDashCollection limit bucketing", () => {
+	let db: Kysely<Database>;
+
+	beforeEach(async () => {
+		db = await setupTestDatabaseWithCollections();
+	});
+
+	afterEach(async () => {
+		await teardownTestDatabase(db);
+	});
+
+	async function createPublishedPost(title: string) {
+		const result = await handleContentCreate(db, "post", {
+			data: { title },
+			status: "published",
+		});
+		if (!result.success) throw new Error("Failed to create post");
+		return result.data!.item;
+	}
+
+	it("a sliced bucket fetch produces the same entries and nextCursor as a direct loader call at the same limit", async () => {
+		for (let i = 1; i <= 7; i++) await createPublishedPost(`Post ${i}`);
+
+		const loader = emdashLoader();
+		const direct = await runWithContext({ editMode: false, db }, () =>
+			loader.loadCollection!({ filter: { type: "post", limit: 4 } }),
+		);
+		expect(direct.entries).toHaveLength(4);
+		expect(direct.nextCursor).toBeTruthy();
+
+		const bucketed = await runWithContext({ editMode: false, db }, () =>
+			loader.loadCollection!({ filter: { type: "post", limit: 10 } }),
+		);
+		expect(bucketed.entries).toHaveLength(7);
+		const sliced = sliceCollectionResult(bucketed, 4, undefined);
+
+		expect(sliced.entries.map((e) => e.id)).toEqual(direct.entries.map((e) => e.id));
+		expect(sliced.nextCursor).toBe(direct.nextCursor);
+	});
+
+	it("bucketFilter raises small limits and leaves large ones alone", () => {
+		expect(bucketFilter(undefined)).toEqual({ fetchFilter: undefined, requestedLimit: undefined });
+		expect(bucketFilter({ limit: 4 })).toEqual({ fetchFilter: { limit: 10 }, requestedLimit: 4 });
+		expect(bucketFilter({ limit: 9 })).toEqual({ fetchFilter: { limit: 10 }, requestedLimit: 9 });
+		expect(bucketFilter({ limit: 10 })).toEqual({
+			fetchFilter: { limit: 10 },
+			requestedLimit: undefined,
+		});
+		expect(bucketFilter({ limit: 50 })).toEqual({
+			fetchFilter: { limit: 50 },
+			requestedLimit: undefined,
+		});
+		// cursor-paginated calls bypass bucketing — pagination contract requires honouring the limit
+		expect(bucketFilter({ limit: 4, cursor: "abc" })).toEqual({
+			fetchFilter: { limit: 4, cursor: "abc" },
+			requestedLimit: undefined,
+		});
+	});
+
+	it("paginating from a slice-produced cursor returns the correct next page", async () => {
+		for (let i = 1; i <= 7; i++) await createPublishedPost(`Post ${i}`);
+
+		const loader = emdashLoader();
+		const bucketed = await runWithContext({ editMode: false, db }, () =>
+			loader.loadCollection!({ filter: { type: "post", limit: 10 } }),
+		);
+		const firstPage = sliceCollectionResult(bucketed, 4, undefined);
+		expect(firstPage.entries).toHaveLength(4);
+		expect(firstPage.nextCursor).toBeTruthy();
+
+		const secondPage = await runWithContext({ editMode: false, db }, () =>
+			loader.loadCollection!({
+				filter: { type: "post", limit: 4, cursor: firstPage.nextCursor },
+			}),
+		);
+		expect(secondPage.entries).toHaveLength(3);
+
+		const allIds = [...firstPage.entries, ...secondPage.entries].map((e) => e.id);
+		expect(new Set(allIds).size).toBe(7);
+	});
+});